Solve for $x$ and $y$ by deriving an expression for $y$ from the second equation, and substituting it back into the first equation. $\begin{align*}-7x+2y &= 4 \\ 4x+4y &= 8\end{align*}$
Explanation: Begin by moving the $x$ -term in the second equation to the right side of the equation. $4y = -4x+8$ Divide both sides by $4$ to isolate $y$ $y = {-x + 2}$ Substitute this expression for $y$ in the first equation. $-7x+2({-x + 2}) = 4$ $-7x - 2x + 4 = 4$ Simplify by combining terms, then solve for $x$ $-9x + 4 = 4$ $-9x = 0$ $x = 0$ Substitute $0$ for $x$ back into the top equation. $-7( 0)+2y = 4$ $2y = 4$ $2y = 4$ $y = 2$ The solution is $\enspace x = 0, \enspace y = 2$.